Caption: This roundabout in Richland Township may be joined by others now being planned in Berks County by PennDOT.

Headline:Is the roundabout our solution for traffic jams?

Roundabouts could be coming to an intersection near you.

So what is a roundabout? It's a type of traffic circle at which approaching motorists must yield to those already inside.

Officially, roundabouts are not traffic circles. Traffic circles are larger and motorists entering the circle have the right-of-way. Roundabouts are compact models granting the right to proceed to drivers already inside, forcing entering vehicles to yield.

Try to remember all that as your knuckles whiten on your next approach.

More popular in Europe, roundabouts have been making inroads in the United States. The Federal Highway Administration has been urging engineers to consider them when planning roads or major rehabilitation projects, and the Pennsylvania Department of Transportation has adopted a similar policy.

When properly designed and implemented under the right conditions -- generally lesser-traveled roads on relatively flat terrain -- roundabouts tend to be safer because they preclude the possibility of head-on or "T-bone" side-impact crashes at high speeds. They also help "calm" traffic by forcing motorists to slow down in the circular lanes.

"They're designed to operate at low speeds -- the radii that are used, the circumference of the roundabout, [everything is] designed to control the speed of traffic, to eliminate those high-speed angle crashes you have at a signalized intersection," Toomey said.

Despite the slower speeds, studies show roundabouts generally reduce traffic delays compared with intersections with signals, where only half the traffic is moving at any given time.

Roundabouts are being considered as part of PennDOT's planning for the renovation of three Berks County intersections on Route 222 west of Kutztown, between Fleetwood and Blandon. They could replace the standard intersections of Routes 662 and 73, and of Genesis Drive.

Of the three, Toomey said the Route 662 crossing appears to be the most viable candidate for conversion to a roundabout. Berks County Transportation Planner Alan Piper agreed, noting that Route 73 and Genesis Drive might prove problematic, in part because of topography, a high proportion of truck traffic and other factors.

It's also possible that widened standard intersections with better traffic signals and related improvements will be chosen for all three intersections, Piper said. The project is in the preliminary engineering stage, and no decisions have been made. The start of construction on the estimated $16 million to $17 million project is at least two years down the road, according to Piper.

The Federal Highway Administration has been urging highway planners and engineers to consider roundabouts as replacements for signal-controlled intersections for at least a decade.

"Many international studies have found that one of the most significant benefits of a roundabout installation is the improvement in overall safety performance," states an FHWA guide on the issue from 2000.

One study cited in the report found that roundabouts reduced crash frequency by an average of 37 percent, and that roundabout accidents tended to be less violent and result in fewer and less-severe injuries.

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Current Comments

For years now, I use the circle 'roundabout' at routes 31/202 in Flemington NJ every day, and it's very useful and not stressful, if the planners don't try to load too many dictates into it. There's plenty of tractor-trailer truck traffic through there.

The other 'roundabout' just a few yards away - at route 12/main street - is a white knuckle affair due to it's tiny size, the planners attempting to squeeze two lanes out of the width of the roadway, the planners painted lines that don't facilitate easy predictable traffic movement, tilting the road to the right causing an unsettling sensation that doesn't go away at any speed, and signs that are not easily understood by those who are most likely to need that information.

I'm in a 5 ton box truck on those circles daily, and if I were to design a circle that was hostile to drivers, the only thing I'd need to add to the Rt12/main street circle would be a couple raised concrete islands at the exits to heighten the unease and sense of danger all around. Seriously, I hate that circle.

Posted By: Jason N | Mar 5, 2011 12:21:52 AM

Those aren't roundabouts (12/Main or 31/202), not the modern roundabouts that are being proposed, anyway. Those are rotaries. Many people confuse older styles of circular intersections with modern roundabouts. Visit www.ksu.edu to see the differences. www.fhwa.dot.gov has a video about modern roundabouts that is mostly accurate. One easy way to tell the difference is size. Two-lane modern roundabouts top out at about 220 feet in diameter.
Modern roundabouts are the safest form of intersection in the world. Visit www.iihs.org for safety facts. The safety comes from the ‘slow and go’ operation instead of the ‘stop or go fast’ way a stop light works (or the ‘keep going fast’ large traffic circle fantasy). This is the #1 reason there are over 2,100 modern roundabouts in the US today and many more on the way. Slow and go also means less delay than a stop light, especially the other 20 hours a day people aren’t driving to or from work.
As for capacity, single lane modern roundabouts handle typical intersections of up to 20,000 entering vehicles per day while the two-lane versions work up to 50,000 vehicles per day. Slip lanes for high volume right turns move even more traffic.

Posted By: ScottRAB | Mar 7, 2011 1:42:39 PM

Let me bed if you are curious to pass as article writer for me? I can move $10/article.

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about this blog

Morning Call Reporter and Columnist Dan Hartzell is The Road Warrior, defending the drivers of the Lehigh Valley and the roads on which they drive. E-mail questions about transportation in the Lehigh Valley and beyond to hartzell@mcall.com.